Method for finishing anti-friction bearings

ABSTRACT

A method for refurbishing used assembled anti-friction bearings in which the bearings are first given a preliminary washing with a solvent and the seals and shields on the bearing are removed. The bearing is then placed in a vibratory finishing mill having a quantity of finishing material therein which acts upon and finishes the bearing for a predetermined period of time. The finishing media is then washed from the bearing, the bearing is lubricated and new shields are replaced. The final finishing of new bearings may also be accomplished in accordance with the method disclosed herein.

United States Patent [1 1 Frost et al.

[451 Aug. 14, 1973 E. Shaw, Grandville; Siegirled K. Weiss, GrandRapids, all of Mich.

[73] Assignee: Forst Engineered Products, Inc.,

Grand Rapids, Mich.

[22] Filed: June 30, 1971 [21] Appl. No.: 158,311

[56] References Cited UNITED STATES PATENTS 4/1951 Howe 51/316 X 9/1969Balz 51/163 3,248,826 5/1966 Van Fossen 51/316 1,946,440 2/1934 Herrmann3,256,643 6/1966 Sudarsky .Q 51/313 X Primary Examiner-Donald G. KellyAtt0rney--Price, Heneveld, l-luizenga & Cooper ABSTRACT A method forrefurbishing used assembled anti-friction bearings in which the bearingsare first given a preliminary washing with a solvent and the seals andshields on the bearing are removed. The bearing is then placed in avibratory finishing mill having a quantity of finishing material thereinwhich acts upon and finishes the bearing for a predetermined period oftime. The finishing media is then washed from the bearing, the bearingis lubricated and new shields are replaced. The final finishing of newbearings may also be accomplished in accordance with the methoddisclosed herein.

10 Claims, 4 Drawing Figures Patented Aug. 14, 1973 3,751,861

INVENTORS CHARLES C. FROST Y THOMAS E. SHAW K. WElS/S I W W ATTOR YSMETHOD FOR FINISHING ANTI-FRICTION BEARINGS BACKGROUND OF THE INVENTIONThis invention relates to the finishing of new bearings as well as tothe refurbishing of used bearings particularly of the ball, rollers, orneedle'bearing-type commonly known as anti-friction bearings.

Bearings of this type which provide for a rolling contact between a pairof relatively movable members usually comprise a pair of hardened steelring members or raceways between which one or more sets of hardenedsteel balls, rollers or needles are located. A cage or separator membermay also be provided to keep the rolling elements at the proper distancefrom each other. In some cases, the separator is not provided and therolling elements are positioned adjacent each other. Oil seals and/ordirt shields may also be provided to prevent the entrance ofcontaminating materials between raceways and to retain lubricatingmaterials therein.

Bearings of this type must be manufactured to a high degree of accuracy.Critical machining of the raceways is required as well as criticalmachining and selection of the rolling elements to insure the greatestantifriction capabilities. Obviously, such bearings are relativelyexpensive and when they become worn or con- LII taminated, it isdesirable, if possible to refurbish the bearing to extend its usefulservice life. Obviously, the cost of refurbishing a bearing isconsiderably less than that of the production of a new bearing. However,rebuilding of such bearings has, in the past, been a time consuming,laborious task requiring specialized machinery, in fact, much the samemachinery is required in rebuilding a bearing as is required in theproduction of a new bearing.

A typical ball bearing is generally rebuilt in the following manner. (1The bearings are first preliminarily washed in a solvent to removeaccumulated external dirt, grease and the like. (2) The oil seals andshields are removed. (3) The retainer element is opened so that therolling elements can be removed and discarded and the raceways areseparated. (4) The inner and outer races are ground and honed to propersize. (5) After refinishing, the inner and outer races are gaged andmatched according to their size. (6) The bearing is assembled using newrolling elements and retainers and lubricated. (7) New seals and shieldsare replaced and (8) The bearing is tested.

Many of the aforementioned steps require specialized machines andequipment. In addition, as the bearing is disassembled, the rollingelement retainer is destroyed and the rolling elements are discardedtherefore requiring replacement of rolling elements and retainers. Thegrinding and honing operations are time consuming. The assembly of thebearing itself is a very specialized task requiring specializedmachinery.

In the past, it has always been considered necessary by those skilled inthe art to completely disassemble the bearing as above described inorder to refinish it. Various attempts have been made to clean bearingsusing pressurized abrasive devices, i.e., sand blasting, abrasivesolvents and the like. These procedures, however, have not met withsuccess as microsopic surface imperfections or false brinelling oftenoccurs in the raceways resulting in a useless bearing.

While the above-described techniques for refinishing or rebuildingbearings is time consuming and relatively costly, it is effective inthat bearings rebuilt in such a manner have a service life equal to thatof an original bearing.

SUMMARY OF THE INVENTION We have discovered a new method whereinbearings may be refurbished without complete disassembly thereof,without separate grinding and honing operations on the raceways, withoutreplacement of the rolling elements, without size gaging or matching ofparts for reassembly and without destruction of any of the bearingretaining elements thereby eliminating the necessity for replacing thoseparts. Consequently, with our discovery, time, labor and equipment costsare considerably reduced.

- Basically, the method of the present invention involves the use of avibratory finishing mill having a quantity of ceramic finishing mediatherein to act upon a bearing placed in the media. The shields and sealsare first removed from the ends of the bearing prior to its placement inthe finishing media to allow the media to probe into and around theinner portions of the bearings, rolling elements, the raceways and therolling element retainer.

It is a primary object of this invention therefore to provide a methodfor refurbishing anti-friction bearings.

It is another object of the invention to provide a method forrefurbishing a bearing without disassembly thereof.

It is another object of this invention to provide a method forrefurbishing bearings that is comparatively low in cost. It is anotherobject of this invention to provide an anti-friction bearingrefurbishing method which requires a minimum of time, labor andequipment. Still, another object of this invention to provide a methodof final finishing new anti-friction bearings. Other objects, andaspects and the many advantages of this invention willbecome apparent tothose skilled in the art from a study of this disclosure, the drawingsand the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be describedwith reference to the accompanying drawings in which:

FIG. 1 is a top plan view illustrating a bearing which may be processedin accordance with the teachings of this invention;

FIG. 2 is a cross-sectional view of the bearing of FIG. 1 taken alongthe plane 2-2.

FIG. 3 is a perspective view of a vibratory finishing mill which may beutilized in the practice of this invention; and

FIG. 4 is a perspective view of an individual fragment of the finishingmedia which operates upon the bearing in the practice of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A typical anti-friction bearing10 of the type which may be refurbished in accordance with thisinvention is illustrated in FIGS. 1 and 2. The bearing 10 is ofconventional construction having an inner race 12, an outer race 14 anda plurality of rolling elements or hardened steel balls l6centrallylocated between the inner and outer races. As is well known to thoseskilled in the art, the rolling elements 16 are positioned in grooves orraceways 17 located about the outer diameter of the inner race and theinner diameter of the outer race. A separator or cage element 18 servesto keep the rolling elements at the proper distance from each other.

A vibratory finishing mill 20 which may be utilized in the practice ofthis invention is illustrated in FIG. 3 and is of conventionalconstruction. Basically, the finishing mill comprises a lower base ormounting member 22 and an upper toroidal shaped bowl or hopper 24. Thehopper is supported above the base on a plurality of support springs 26.An electric motor (not shown) located within the base is connected byits drive shaft to the bowl. Eccentric weights (not shown) are connectedto the drive shaft to impart a vibratory motion to the bowl when themotor is operated. When operated, the motor weights and support springsgive the bowl a high frequency tilting and rolling movement with bothhorizontal and vertical amplitudes.

The bowl 24 is essentially toroidal shaped and has a quantity offinishing media contained therein. An individual fragment of such media30 is illustrated in FIG. 4. The preferred media utilized in thepractice of this invention is made of a ceramic material and is of thetype commonly known as an angle cylinder. As the name implies, theceramic material is cylindrical in shape and has each of its ends 32 cutat an angle. The diameter and length of the angle cylinders may varydepending upon the size of the bearings being refurbished. Obviously,other ceramic media such as stars, cones or triangles may be used as iswell known to those skilled in the art of vibratory finishing.

As a practical example of the practice of this invention the materialand equipment utilized for refurbishing a conventional standard '203bearing will be described in detail. To refurbish a quantity of bearingsof the type specified above, we have utilized a vibratory finishing millhaving a bowl capacity of approximately 3 cubic feet which willaccommodate up to 800 pounds of parts and media. One type of finishingmill suitable for use in the practice of this invention is availablefrom SWECO INC., 61 ll East Bandini Boulevard, Los Angeles, Calif.,90054, and is referred to as a Vibro- Energy Finishing Mill and isfurnished under SWECO INC. model number FMD 3 HA.

A ceramic finishing material made for use in the above describedvibratory mill is also available from SWECO INC. An angle cylinder typeof media 30 illustrated in FIG. 4 is preferred. This media has adiameter of five-eighths of an inch and a length of 1- /6 inches, theangle being cut at approximately 30. This is available from SWECO INC.under their part designation F -8 which is a media suitable for milddeburring and fine finishing operations.

Prior to the finishing operation in the mill the bearings are washed ina solvent to remove external dirt, grease and the like and, if theyexist, all shields and seals are removed. A quantity of the abovedescribed media and bearings are then placed in the hopper of the milland the mill is started by means of a switch 28 located on the mill andoperated in a conventional manner.

The parts and media travel a spiral orbital path in the circulartoroidal bowl. The action of the motor weights and support springs givethe bowl a high-frequently tilting and rolling movement, with highhorizontal and vertical amplitudes. This motion of the bowl causes themedia to provide both shearing and peening action against the bearings.As the bearings and media are subjected to vibration the differences inmass between the bearings and media cause relative movementtherebetween. As the bearing moves through the media various surfaces ofmedia and bearing are presented to each other. The angle cylinders roll,slide and penetrate into crevices and openings in the bearings.Extremely small bits and pieces of media break away from the anglecylinders and work even further into and through the most remote areasand hidden crevices of the bearing to effectively clean and final finishall surfaces of the bearing.

After the mill is operated a length of time sufficient to thoroughlyclean the bearings, generally about 2 hours for a size 203 bearing, theyare removed, washed with a solvent and lubricated. New shields and sealsare then replaced and the bearings are tested in a conventional manneras for a new bearing. The bearings are then ready for reuse.

As compared to the above-described prior method, the steps forrefurbishing a bearing when practicing this invention are as follows:(1) Preliminary wash and removal of external dirt; (2) Removal ofshields and seals; (3) Subject the bearing for a time in the vibratorymill; (4) Wash; (5) Lubricate and replace new seals and shields; and (6)Test.

Utilizing our invention, the steps of disassembly, grinding and honingof the bearing races, sizing of the parts and assembly with new rollingelements and retainers have been eliminated. Obviously there is a greatsavings alone in the cost of new rolling elements and retainers.

We have also found that new anti-friction bearings may also be producedin accordance with the teachings of this invention. In the case of newbearings, they are manufactured in a conventional manner except that thefinal finishing operation, that is the final finishing or honing andgrinding of the bearing surfaces may be eliminated. The bearing isassembled in a somewhat unfinished state and is then placed with themedia in the vibratory mill and operated on as previously described. Thefinishing media provides the final finish to the bearing which isnormally performed in a plurality of separate operations.

It may therefore readily be seen that the invention described provides amethod for refurbishing old bearings as well as a method for finishingnew bearings. There is a great reduction in time, labor and equipmentresulting in the production of new bearings and the refurbishing of usedbearings at reduced cost and with great efficiency.

Other modifications and variations will of course be suggested to thoseskilled in the art without departing from the scope of the inventionwhich is defined by the following claims.

We claim:

1. A method of finishing an anti-friction bearing having an inner race,an outer race, and a plurality of rolling elements spaced between saidraces comprising the steps of:

a. placing said bearing together with an abrasive finishing media in avibratory finishing mill;

b. operating said mill to subject said bearing and said media to avibratory action for a period of time sufficient to finish said bearing;

c. removing said bearing from said media; and

d. cleaning said media from said bearing.

2. The method of finishing a bearing as described in claim 1 whereinsaid vibratory action is a relatively high frequency tilting and rollingaction having relatively high amplitude horizontal and verticalcomponents.

3. The method of finishing a bearing as described in claim 2 and furtherincluding the steps of lubricating the bearing and testing the bearing.

4. A method of finishing an anti-friction bearing having an inner race,an outer race, and a plurality of rolling elements spaced between saidraces comprising the steps of:

a. assembling an infinished inner race and an unfinished outer racetogether with a plurality of rolling elements therebetween;

b. placing said unfinished inner face, outer race and rolling elementstogether with an abrasive finishing media in a vibratory finishing mill;and

c. operating said mill to subject said bearing in its assembled state toa vibratory action in the presence of said abrasive finishing media fora period of time sufficient to finish said bearing.

5. The method of finishing a bearing as described in claim 4 whereinsaid vibratory action is a relatively high frequency tilting and rollingaction having relatively high amplitude horizontal andvertical-components.

6. The method of finishing bearings as described in claim 4 and furtherincluding the steps of removing said bearing from said mill and saidmedia; and cleaning said media from said bearing.

7. The method of finishing bearings as described in claim 6 and furthercomprising the steps of lubricating said bearing and testing saidbearing.'

8. A method of finishing bearings as described in claim 4 and furtherincluding the steps of:

a. removing said finished bearing from said vibratory finishing mill;

b. removing said abrasive finishing material from said bearing; and

c. lubricating said bearing.

9. A method of refurbishing used anti-friction bearings comprising thesteps of:

a. washing said bearing in a solvent;

b. placing said washed bearing in an abrasive finishing material in avibratory finishing mill;

c. operating said mill for a period of time sufficient to clean saidbearing;

d. removing said bearing from said mill;

e. cleaning said media from said bearing; and

f. lubricating said bearing.

10. The method of refurbishing an anti-friction bearing as described inclaim 9 wherein said vibratory action is a relatively high frequencytilting and rolling action having relatively high amplitude horizontaland vertical components.

22 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3751 861 Dated August 14 1973 Imventor(s) Charles C. Frost, et a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

[73] Assignee ---"Forst" should be -Frost- Signed and sealed this 18thday of December 1973.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. U 7 RENE D. TEG'IMEYER Attesting Officer ActingCommissionerof Patents

1. A method of finishing an anti-friction bearing having an inner race,an outer race, and a plurality of rolling elements spaced between saidraces comprising the steps of: a. placing said bearing together with anabrasive finishing media in a vibratory finishing mill; b. operatingsaid mill to subject said bearing and said media to a vibratory actionfor a period of time sufficient to finish said bearing; c. removing saidbearing from said media; and d. cleaning said media from said bearing.2. The method of finishing a bearing as described in claim 1 whereinsaid vibratory action is a relatively high frequency tilting and rollingaction having relatively high amplitude horizontal and verticalcomponents.
 3. The method of finishing a bearing as described in claim 2and further including the steps of lubricating the bearing and testingthe bearing.
 4. A method of finishing an anti-friction bearing having aninner race, an outer race, and a plurality of rolling elements spacedbetween said races comprising the steps of: a. assembling an infinishedinner race and an unfinished outer race together with a plurality ofrolling elements therebetween; b. placing said unfinished inner race,outer race and rolling elements together with an abrasive finishingmedia in a vibratory finishing mill; and c. operating said mill tosubject said bearing in its assembled state to a vibratory action in thepresence of said abrasive finishing media for a period of timesufficient to finish said bearing.
 5. The method of finishing a bearingas described in claim 4 wherein said vibratory action is a relativelyhigh frequency tilting and rolling action having relatively highamplitude horizontal and vertical components.
 6. The method of finishingbearings as describEd in claim 4 and further including the steps ofremoving said bearing from said mill and said media; and cleaning saidmedia from said bearing.
 7. The method of finishing bearings asdescribed in claim 6 and further comprising the steps of lubricatingsaid bearing and testing said bearing.
 8. A method of finishing bearingsas described in claim 4 and further including the steps of: a. removingsaid finished bearing from said vibratory finishing mill; b. removingsaid abrasive finishing material from said bearing; and c. lubricatingsaid bearing.
 9. A method of refurbishing used anti-friction bearingscomprising the steps of: a. washing said bearing in a solvent; b.placing said washed bearing in an abrasive finishing material in avibratory finishing mill; c. operating said mill for a period of timesufficient to clean said bearing; d. removing said bearing from saidmill; e. cleaning said media from said bearing; and f. lubricating saidbearing.
 10. The method of refurbishing an anti-friction bearing asdescribed in claim 9 wherein said vibratory action is a relatively highfrequency tilting and rolling action having relatively high amplitudehorizontal and vertical components.